* [PATCH 1/3] diff: use filespec path to set up tempfiles for ext-diff
2023-01-06 11:00 ` [PATCH 0/3] fixing "diff --relative" with external diff Jeff King
@ 2023-01-06 11:03 ` Jeff King
2023-01-06 12:48 ` Junio C Hamano
2023-01-06 11:04 ` [PATCH 2/3] diff: clean up external-diff argv setup Jeff King
2023-01-06 11:05 ` [PATCH 3/3] diff: drop "name" parameter from prepare_temp_file() Jeff King
2 siblings, 1 reply; 7+ messages in thread
From: Jeff King @ 2023-01-06 11:03 UTC (permalink / raw)
To: Carl Baldwin; +Cc: Junio C Hamano, Git Mailing List
When we're going to run an external diff, we have to make the contents
of the pre- and post-images available either by dumping them to a
tempfile, or by pointing at a valid file in the worktree. The logic of
this is all handled by prepare_temp_file(), and we just pass in the
filename and the diff_filespec.
But there's a gotcha here. The "filename" we have is a logical filename
and not necessarily a path on disk or in the repository. This matters in
at least one case: when using "--relative", we may have a name like
"foo", even though the file content is found at "subdir/foo". As a
result, we look for the wrong path, fail to find "foo", and claim that
the file has been deleted (passing "/dev/null" to the external diff,
rather than the correct worktree path).
We can fix this by passing the pathname from the diff_filespec, which
should always be a full repository path (and that's what we want even if
reusing a worktree file, since we're always operating from the top-level
of the working tree).
The breakage seems to go all the way back to cd676a5136 (diff
--relative: output paths as relative to the current subdirectory,
2008-02-12). As far as I can tell, before then "name" would always have
been the same as the filespec's "path".
There are two related cases I looked at that aren't buggy:
1. the only other caller of prepare_temp_file() is run_textconv(). But
it always passes the filespec's path field, so it's OK.
2. I wondered if file renames/copies might cause similar confusion.
But they don't, because run_external_diff() receives two names in
that case: "name" and "other", which correspond to the two sides of
the diff. And we did correctly pass "other" when handling the
post-image side. Barring the use of "--relative", that would always
match "two->path", the path of the second filespec (and the rename
destination).
So the only bug is just the interaction with external diff drivers and
--relative.
Reported-by: Carl Baldwin <carl@ecbaldwin.net>
Signed-off-by: Jeff King <peff@peff.net>
---
diff.c | 2 +-
t/t4045-diff-relative.sh | 29 +++++++++++++++++++++++++++++
2 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/diff.c b/diff.c
index 9b14543e6e..59039773a1 100644
--- a/diff.c
+++ b/diff.c
@@ -4281,7 +4281,7 @@ static void add_external_diff_name(struct repository *r,
const char *name,
struct diff_filespec *df)
{
- struct diff_tempfile *temp = prepare_temp_file(r, name, df);
+ struct diff_tempfile *temp = prepare_temp_file(r, df->path, df);
strvec_push(argv, temp->name);
strvec_push(argv, temp->hex);
strvec_push(argv, temp->mode);
diff --git a/t/t4045-diff-relative.sh b/t/t4045-diff-relative.sh
index 198dfc9190..9b46c4c1be 100755
--- a/t/t4045-diff-relative.sh
+++ b/t/t4045-diff-relative.sh
@@ -164,6 +164,35 @@ check_diff_relative_option subdir file2 true --no-relative --relative
check_diff_relative_option . file2 false --no-relative --relative=subdir
check_diff_relative_option . file2 true --no-relative --relative=subdir
+test_expect_success 'external diff with --relative' '
+ test_when_finished "git reset --hard" &&
+ echo changed >file1 &&
+ echo changed >subdir/file2 &&
+
+ write_script mydiff <<-\EOF &&
+ # hacky pretend diff; the goal here is just to make sure we got
+ # passed sensible input that we _could_ diff, without relying on
+ # the specific output of a system diff tool.
+ echo "diff a/$1 b/$1" &&
+ echo "--- a/$1" &&
+ echo "+++ b/$1" &&
+ echo "@@ -1 +0,0 @@" &&
+ sed "s/^/-/" "$2" &&
+ sed "s/^/+/" "$5"
+ EOF
+
+ cat >expect <<-\EOF &&
+ diff a/file2 b/file2
+ --- a/file2
+ +++ b/file2
+ @@ -1 +0,0 @@
+ -other content
+ +changed
+ EOF
+ GIT_EXTERNAL_DIFF=./mydiff git diff --relative=subdir >actual &&
+ test_cmp expect actual
+'
+
test_expect_success 'setup diff --relative unmerged' '
test_commit zero file0 &&
test_commit base subdir/file0 &&
--
2.39.0.463.g3774f23bc9
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 2/3] diff: clean up external-diff argv setup
2023-01-06 11:00 ` [PATCH 0/3] fixing "diff --relative" with external diff Jeff King
2023-01-06 11:03 ` [PATCH 1/3] diff: use filespec path to set up tempfiles for ext-diff Jeff King
@ 2023-01-06 11:04 ` Jeff King
2023-01-06 11:05 ` [PATCH 3/3] diff: drop "name" parameter from prepare_temp_file() Jeff King
2 siblings, 0 replies; 7+ messages in thread
From: Jeff King @ 2023-01-06 11:04 UTC (permalink / raw)
To: Carl Baldwin; +Cc: Junio C Hamano, Git Mailing List
Since the previous commit, setting up the tempfile for an external diff
uses df->path from the diff_filespec, rather than the logical name. This
means add_external_diff_name() does not need to take a "name" parameter
at all, and we can drop it. And that in turn lets us simplify the
conditional for handling renames (when the "other" name is non-NULL).
Signed-off-by: Jeff King <peff@peff.net>
---
diff.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/diff.c b/diff.c
index 59039773a1..72bed1d0a3 100644
--- a/diff.c
+++ b/diff.c
@@ -4278,7 +4278,6 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
static void add_external_diff_name(struct repository *r,
struct strvec *argv,
- const char *name,
struct diff_filespec *df)
{
struct diff_tempfile *temp = prepare_temp_file(r, df->path, df);
@@ -4308,11 +4307,9 @@ static void run_external_diff(const char *pgm,
strvec_push(&cmd.args, name);
if (one && two) {
- add_external_diff_name(o->repo, &cmd.args, name, one);
- if (!other)
- add_external_diff_name(o->repo, &cmd.args, name, two);
- else {
- add_external_diff_name(o->repo, &cmd.args, other, two);
+ add_external_diff_name(o->repo, &cmd.args, one);
+ add_external_diff_name(o->repo, &cmd.args, two);
+ if (other) {
strvec_push(&cmd.args, other);
strvec_push(&cmd.args, xfrm_msg);
}
--
2.39.0.463.g3774f23bc9
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 3/3] diff: drop "name" parameter from prepare_temp_file()
2023-01-06 11:00 ` [PATCH 0/3] fixing "diff --relative" with external diff Jeff King
2023-01-06 11:03 ` [PATCH 1/3] diff: use filespec path to set up tempfiles for ext-diff Jeff King
2023-01-06 11:04 ` [PATCH 2/3] diff: clean up external-diff argv setup Jeff King
@ 2023-01-06 11:05 ` Jeff King
2 siblings, 0 replies; 7+ messages in thread
From: Jeff King @ 2023-01-06 11:05 UTC (permalink / raw)
To: Carl Baldwin; +Cc: Junio C Hamano, Git Mailing List
The prepare_temp_file() function takes a diff_filespec as well as a
filename. But it is almost certainly an error to pass in a name that
isn't the filespec's "path" parameter, since that is the only thing that
reliably tells us how to find the content (and indeed, this was the
source of a recently-fixed bug).
So let's drop the redundant "name" parameter and just use one->path
throughout the function. This simplifies the interface a little bit, and
makes it impossible for calling code to get it wrong.
Signed-off-by: Jeff King <peff@peff.net>
---
diff.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/diff.c b/diff.c
index 72bed1d0a3..329eebf16a 100644
--- a/diff.c
+++ b/diff.c
@@ -4213,7 +4213,6 @@ static void prep_temp_blob(struct index_state *istate,
}
static struct diff_tempfile *prepare_temp_file(struct repository *r,
- const char *name,
struct diff_filespec *one)
{
struct diff_tempfile *temp = claim_diff_tempfile();
@@ -4231,18 +4230,18 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
if (!S_ISGITLINK(one->mode) &&
(!one->oid_valid ||
- reuse_worktree_file(r->index, name, &one->oid, 1))) {
+ reuse_worktree_file(r->index, one->path, &one->oid, 1))) {
struct stat st;
- if (lstat(name, &st) < 0) {
+ if (lstat(one->path, &st) < 0) {
if (errno == ENOENT)
goto not_a_valid_file;
- die_errno("stat(%s)", name);
+ die_errno("stat(%s)", one->path);
}
if (S_ISLNK(st.st_mode)) {
struct strbuf sb = STRBUF_INIT;
- if (strbuf_readlink(&sb, name, st.st_size) < 0)
- die_errno("readlink(%s)", name);
- prep_temp_blob(r->index, name, temp, sb.buf, sb.len,
+ if (strbuf_readlink(&sb, one->path, st.st_size) < 0)
+ die_errno("readlink(%s)", one->path);
+ prep_temp_blob(r->index, one->path, temp, sb.buf, sb.len,
(one->oid_valid ?
&one->oid : null_oid()),
(one->oid_valid ?
@@ -4251,7 +4250,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
}
else {
/* we can borrow from the file in the work tree */
- temp->name = name;
+ temp->name = one->path;
if (!one->oid_valid)
oid_to_hex_r(temp->hex, null_oid());
else
@@ -4269,7 +4268,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
else {
if (diff_populate_filespec(r, one, NULL))
die("cannot read data blob for %s", one->path);
- prep_temp_blob(r->index, name, temp,
+ prep_temp_blob(r->index, one->path, temp,
one->data, one->size,
&one->oid, one->mode);
}
@@ -4280,7 +4279,7 @@ static void add_external_diff_name(struct repository *r,
struct strvec *argv,
struct diff_filespec *df)
{
- struct diff_tempfile *temp = prepare_temp_file(r, df->path, df);
+ struct diff_tempfile *temp = prepare_temp_file(r, df);
strvec_push(argv, temp->name);
strvec_push(argv, temp->hex);
strvec_push(argv, temp->mode);
@@ -7031,7 +7030,7 @@ static char *run_textconv(struct repository *r,
struct strbuf buf = STRBUF_INIT;
int err = 0;
- temp = prepare_temp_file(r, spec->path, spec);
+ temp = prepare_temp_file(r, spec);
strvec_push(&child.args, pgm);
strvec_push(&child.args, temp->name);
--
2.39.0.463.g3774f23bc9
^ permalink raw reply related [flat|nested] 7+ messages in thread